1. Field of the Invention
The disclosure pertains to compositions and methods useful for controlling corrosion. In particular, the disclosure pertains to corrosion control compositions that do not include any phosphorus and methods of mitigating corrosion of metals in corrosive aqueous systems.
2. Description of the Related Art
Corrosion of metal surfaces in aqueous media has long been a problem for industries such as the oil and gas industry, food/beverage industry, wash/sanitizing industry, pulp and paper, power generation, manufacturing, and utilities. For example, it is well known that during the production of oil and gas several other corrosive components are present such as brines, organic acids, carbon dioxide, hydrogen sulfide, and microorganisms. These aggressive constituents can cause severe corrosion as evidenced by surface pitting, embrittlement, and general loss of metal. The metallic surfaces can be composed of high alloy steels including chrome steels, ferritic alloy steels, austenitic stainless steels, precipitation-hardened stainless steels, and high nickel content steels, copper, and carbon steels.
In the food/beverage and wash/sanitizing industry, solutions such as sodium hypochlorite solutions are commonly used and are highly effective as bleaches and sanitizers for cleaning a variety of surfaces. However, sodium hypochlorite solutions are corrosive to many treated surfaces, in particular, metal surfaces become highly corroded.
There are several mechanisms responsible for corrosion of metals. In corrosive water systems, the overall corrosion rate is controlled by the reduction of oxygen inhibiting the cathodic reaction. However, the most robust and cost effective water treatment programs include both anodic and cathodic inhibitors to block reactions at both the anode and the cathode.
Mitigation of corrosion and fouling is essential in all water based or aqueous systems. In the prior art, most of the additives that are commonly used for corrosion and fouling mitigation include phosphorus, such as orthophosphates, polyphosphates, or organic phosphates commonly known as phosphonates. While there has been some success attributed to phosphorus containing corrosion and fouling inhibitor compositions, it has recently been discovered that phosphorus is not environmentally friendly and thus environmental agencies have either mandated a reduction in its use or banned its use altogether.
As such, there exists a need for corrosion and fouling mitigating compositions that do not include phosphorus, and methods for providing corrosion or fouling mitigation using such non-phosphorus containing compositions.